1. Field of Invention
The present invention relates to a Micro-Electro-Mechanical System (MEMS) sensing device and a method for making the MEMS sensing device, in particular to such MEMS sensing device and method wherein a packaging process is integrated in the manufacturing process for making the device.
2. Description of Related Art
MEMS devices are miniature devices integrating electrical and mechanical functions, and often made by semiconductor processes. Typical commercial products of such devices include pressure sensors, accelerators, gyroscopes, optical telecom devices, digital light processors (DLPs), inkjet heads, RF sensing devices for wireless network and so on. They are applied to vehicle tire pressure gauges, optical telecom networks, projectors, sensing networks, digital microphones, clock oscillators, interactive gamers and several other kinds of products. The MEMS devices also play major roles even in many developed researches of new generation memory techniques, biochips, display techniques, and emerging energies.
Traditional MEMS chips require complicated assembling (or packaging) processes, such as QFN (Quad Flat No leads) or LGA (Land Grid Array), so that they can be applied to and combined in the foregoing products. FIG. 1 shows a cross-sectional diagram of a prior art pressure sensor. As shown in FIG. 1, the pressure sensor 10 comprises a MEMS chip 11, a packaging housing 13, an insulating adhesive 15, a plurality of bonding wires 17 and a QFN leadframe 19. The MEMS chip 11 is mounted on the die pad 193 of the QFN leadframe 19, and is electrically connected to the contacts 191 of the QFN leadframe 19 through the bonding wires 17. The packaging housing 13 covers the MEMS chip 11, and is bonded with the QFN leadframe 19. The through hole 131 of the packaging housing 13 allows external air outside the pressure sensor 10 to directly pressure the MEMS chip 11, so that the external air pressure can be measured. However, manufacturing such QFN or LGA type MEMS devices require complicated packaging processes and multiple materials some of which are not commonly used in a typical CMOS semiconductor process. Thus, the cost is undesirably high.
In view of above disadvantages, the present invention provides a method for making a MEMS sensing device that integrates a wafer level packaging process after a CMOS process, so that the packaging process is simplified and the manufacturing cost is also reduced.
For reference, the following patents disclose contents related to the present application: U.S. Pat. Nos. 6,012,336, 6,536,281, 6,928,879, 7,121,146, 6,743,654, and 7,135,749.